Tubular member for use in well drilling operations



Aug. 23, 1966 1.. w. TOELKE 3,267,695

TUBULAR MEMBER FOR USE IN WELL DRILLING OPERATIONS Fixed March 29. 1965 2 Shawls-Sheet 1 is: far W. Toe/A e INVENTOR.

ATTO/PIVEJ J United States Patent 3,267,695 TUBULAR MEMBER FOR USE IN WELL DRILLING OPERATIONS Lester W. Toelke, 2368 A2 Bingle Eoad, Bldg. E, Houston, Tex. Filed Mar. 29, 1965, Ser. No. 443,362 9 (Zlaims. ((Zl. 64-1) The present application is a continuation-in-part of my prior copending application Serial No. 204,420, filed June 22, 1962, for Tubular Member for Use in Well Drilling Operations, now United States Letters Patent No. 3,175,- 374, issued March 30, 1965.

The present invention relates to a tubular member for use in well drilling operations, and more particularly, to the surface arnangement of a drill string tubular member used in the drilling of Wells.

In the rotary drilling of wells, a drilling bit is normally supported on the lower end of a drill string, the drill string extending upwardly to the earths surface where rotation is imparted thereto to effect drilling or penetration of the earths surface. The drill string, as generally contemplated at the present time, is composed of a plurality of tubular sections which are adapted to be threadedly engaged at each end, the drill string also including one or more heavy tubular members called drill collars for concentrating a desired weight immediately above the bit to apply weight on the bit in a manner to increase the rate of penetration of the drill bit and to attempt to drill the well in the desired direction or relationship relative to the earths surface.

In some instances, a substantial number of drill collars are positioned in the drill string in an endeavor to apply a substantial weight on the drilling bit; however, the drill string, including the drill collars and the other tubular sections forming the drill string, is of a smaller outer diameter than the size of the bit secured at the lower end thereof, and during drilling operations, a drilling fluid is circulated downwardly through the drill string and discharged through the drill bit and then returned to the earths surface in the annulus surrounding the drill string in the well bore. In most instances, the drill string Will engage or rub against the side of the Well bore during drilling operations. This causes severe, but in most instances, very smooth wear or lapping on one side of the well bore thus effecting a channel or seat which partially envelopes the tubular member sometimes developing a seal between the surface of the channel in the formation in the well and the abutting drill string surface which prevents fluid communication between these abutting surfaces. If this occurs opposite a formation with a lower pressure than the hydrostatic head of the drilling fluid, and if the drilling string is static for a matter of a few seconds, the differential pressure may hold the drilling string against the wall with such force that it cannot be then loosened by normal methods. When the drill string becomes stuck from this cause, it is known as being well stuck; therefore, it is desirable to prevent a fluid seal from developing even though the drill string is against the wall of the well.

The present invention is directed to a drill string incorporting a means which overcomes the above and other problems encountered in connection with the sticking of a drill string in a well bore.

An object of the present invention is to provide a tubular drill string member having a plurality of recesses on its outer peripheral surface to thereby accommodate fluid flow in a turbulent manner around the tubular drill string member at all times during drilling operations and even though the drill string may engage the well bore Wall on one side and thereby inhibit sticking thereof in the well bore.

Still another object is to provide a tubular drill string member formed with a plurality of recesses to create a turbulent flow around the drill string which not only aids in inhibiting the formation of a fluid seal but which aids in destroying a fluid seal if it forms, thereby decreasing the possibility of the tubular member from either becoming or remaining wall stuck.

Yet a further object of the present invention is to provide on a tubular drill string for use in well drilling operations a plurality of circumferentially and longitudinally extending spaced recesses in the outer surface of the tubular member to provide fluid passages of substantial extent even when it is engaged against the side of the well bore so that drilling fluid access to that surface area of the well bore wall contacting the drilling member is effected to thereby inhibit sticking of the drilling member in the well bore.

Various means and methods have been proposed with a View of endeavoring to center the drill string in the well bore to inhibit sticking, and various means of grooving of the drill string have been proposed; however, such procedures generally increase the cost of drilling operations in that they require special equipment. Also, it is desirable to provide a maximum size flow pathfor drilling fluid access circumferentially of the drill string to inhibit clogging or restriction of the fluid flow paths formed on the drill string, and it is desirable to accomplish this with a minimum of forming or grooving on the drill string to thereby reduce the initial cost of preparing the drill string and to inhibit the presence of Weak spots or stress areas in the drill string.

The present invention has for one of its further objects the provision of a plurality of recessed areas which extend circumferentially and longitudinally of the drill string to provide a maximum unrestricted area for fluid flow around the drill string when it is in the well bore.

Still a further object of the present invention is to provide a means for continuous fluid circulation circumferentially of a drill string tubular member even though it may be engaged with one side of the well bore wall.

A further object is to interrupt the normal outer surface of a drill string at a plurality of circumferentially and longitudinally spaced intervals to provide fluid access circumferentially of the drill string.

Still a further object is to provide a plurality of smooth recesses on the surface of a drill string member which recesses are of less longitudinal extent than the drill string member, and which recesses extend circumferentially and longitudinally to interrupt the normal surface at a plurality of spaced longitudinal and circumferential intervals.

Yet another object of the present invention is to provide a means for accomplishing fluid circulation circumferentially of a drill string tubular member even though it may be engaged with one side of the well bore, which means can be provided at a minimum of expense and with a minimum of deleterious effect upon the tubular drill string member.

A further object is to provide a plurality of longitudinally extending recesses spaced on a tubular member so that their ends do not overlap, but arranged so that side edges of the recesses overlap circumferentially.

Still another object of the present invention is to provide a tubular member with an external surface configur-ation which reduces the normal outer circumferential area but without substantially decreasing its strength and to provide for fluid access circumferentially of the tubular drill string member even when it is engaged against the side of the well bore wall.

Yet a further object of the present invention is to provide a means for forming a tubular drill string to inhibit wall sticking thereof in the well bore.

Other objects and advantages of the present invention will become more apparent from a consideration of the following description and drawings wherein:

FIG. 1 is a vertical sectional view of a lower portion of a well bore illustratin partly in elevation a portion of the tubular drill string of the present invention and showing a drill bit secured to the lower end thereof;

FIG. 2 is a sectional view taken along the line iE-S of FIG. 1 to illustrate the circumferential overlap of the side edges of the recesses for accommodating fluid flow circumferentially of the tubular drill string even when it is engaged against one side of the well bore wall;

FIG. 3 is an enlarged view of a portion of the tubular member of FIG. 1 illustrating one form of arranging the recesses on the tubular drill string member to obtain circumferential overlap between recesses adjacent to one another in accordance with the present invention;

FIG. 4 is a transverse sectional view illustrating one form of arranging the recesses on the tubular drill string member in accordance with the present invention;

FIG. 5 is a transverse sectional view illustrating another form of arranging the recesses on the tubular drill string member in accordance with the present invention;

FIG. 6 is a transverse sectional view of a tubular drill string member having circumferentially overlapping recesses with bottom portions defined in sectional view by straight line elements; and

FiG. 7 is a transverse sectional view of the tubular drill string illustrating still another form of the present inven tion wherein the bottom portions of the circumferentially overlapping recesses are convex in sectional view.

Attention is directed to FIG. 2 of the drawings where a portion of a well bore dB is illustrated in sectional view, with a drill string represented generally at 61 therein. it will be noted that the drill string til is shown as having been moved to one side of the well bore 60, and more particularly, seated in a longitudinally formed channel 62 formed in the well bore 63. It can be appreciated from the illustration of FIG. 2 of the drawings that where the pressure existing in the formation 64 immediately adjacent to the well bore 6% withdraws drilling fluid from the well bore, the drilling fluid hydrostatic head in the annulus 63 causes the drill string 61 to be held laterally against the well bore. As previously mentioned, continued rotation of the drill string 61 and gradual lowering thereof as the wellbore so further penetrates the earths subsurface sometimes forms the channel 62 on the side of the well bore against which the drill string 61 rubs. The channel 62 in some instances may extend for a substantial vertical distance along the well bore 60, and may partially envelop the tubular drill string as illustrated in FIG. 2 of the drawings. A rubbing of the drill string against the portion which partially envelops it may create a seal between the drill string surface and the formation surface, and it has been found in practice that under this condition if rotation of the drill string 61 is stopped for even a short period of time, the drill string may become stuck due to differential pressures previously described, thereby preventing further rotation or longitudinal movement of the drill string at within the well bore 6%.

The present invention provides a plurality of longitudinally and circumferentially extending recesses which inhibit sticking of the drill string 61 in the well bore 69. The recesses which are designated generally at 66 are formed on the outer peripheral surface or skin 67 of the tubular drill string 61. The outer peripheral surface 67 is shown in the form of substantially a circle on a plane transverse to the longitudinal axis of the tubular member, and the recesses 65 interrupt the outer peripheral surface 67 to reduce the surface area thereof, but some recess contours may actually increase the total outer surface area of the drill string in which they are formed. As illustrated in the drawings, the recesses d6 are shown as being formed in the drill collar portion 68 of the drill string 61, which drill collars are positioned in the drill string all in close proximity and immediately above the drill bit 69 secured on the lower end of the drill string til.

Attention is further directed to the sectional view of BC. 1 which shows the recesses 56 as being circumferentially spaced and also longitudinally spacedof the drill string 61 and which are of suitable longitudinal and circumferential extent so that liquid communication circumferentially of a substantial longitudinal extent of the drill collar is effected. The design and arrangement of the recesses on the outer surface 6'7 creates a turbulence in the flowing drilling fluid around the drill collar or drill string even when the drill collar es is in contact with the face of the channel 62 formed in the well bore 69 as illustrated in FIG. 2. ate-d aids in preventing a fluid seal from forming in the manner as hereinbefore explained, and aids in destroying any fluid seal that might be formed between the drill collar or drill string and well bore wall.

As is more clearly shown in enlarged views of FIGS. 2 and 3 of the drawings, the recesses represented at 66a which are spaced circumferentially in a row around the tubular member 68 overlap the spaced recesses represented by the numeral 665 in the next adjacent row. The side edges of the recesses dda and 66b are shown in FIG. 2 as circumferentially overlapping wherein the recesses a terminate at the side portions 66a and the recesses 66b in the next adjacent row terminate in the side portions 66b; and as more clearly shown in FIG. 2, overlap each other circumferentially by the amount represented at 7%. It will be appreciated that the overlap is offset longitudinally of the drill string as shown in the drawings, since the end edges 75b of the recesses are spaced longitudinally relative to each other by the amount represented at 743a in FIG. 3. The circumferential overlap of the re ess side edges is more clearly shown in the enlarged view of FIG. 3, as is the longitudinal spacing of the ends 751; of the recesses. entially and spacing longitudinally of adjacent recesses 55 in the outer peripheral surface of the drill string, turbulcnce in the fluid is created around the tubular member as throughout the longitudinal exent which is provided with recesses. Fluid turbulence and communication is maintained even between the face of the slot or channel as in the well bore 68 and the recesses 66 in the outer surface 17 of the tubular members comprising the drill string 61. it can be appreciated that the overlapping relationship of the recesses provides a substantial circumferential outer area of the drill collar 68 which is in fluid communication with the annulus 63 even thoughthe drill string is seated in the channel 62. Thus, a substantial portion of the hydrostatic differential pressure acting to hold the drill collar 63 in the channel 62 on the side of the well bore is relieved.

The arrangement of the recesses 66 on the drill string d1 as illustrated in F568. 1, 2, and 3 of the drawings provides a substantial size flow path for fluid to be circulated to the channel 62 formed on the well bore 69 thereby inhibiting sticking of the drill collar 68 in the channel. Also, it may be appreciated that the recesses 66 may be of any suitable longitudinal and circumferential extent, thereby providing a fluid opening which is of substantial extent and less likely to be clogged by materials or cuttings which may be carried into the drill fluid passing through the annulus 63.

in the particular form of the recesses 66 illustrated in FIGS. 1, 2, and 3 of the drawings, it can be seen that each recess 66 is formed by machining arcuate surfaces '75 in the outer peripheral surface 67 of the drill collar 63 wherein the surfaces '75 are slightly convex as illustrated in the sectional view of FIG. 2. The surfaces gradually slope up to the outer peripheral surface 67 at the side portions 75a to an extent again illustrated by the sectional view of FIG. 2 whereas the end portions 755 slope up to the outer peripheral surface 67 of the drill collar 68 at 7% as illustrated in FIGS. 1 and 3.

The fluid turbulence therebycre- Because of the overlapping circumfer The extent to which the end portions 75b slope up to the outer peripheral surface is best shown in the drawings. The intersection of the side and end portions of the recesses 66 is formed in a manner so as not to form up standing shoulders. This eliminates sharp, upstanding shoulders whch might effect an undesirable scraping action in the well bore 60 when the well string is pulled upwardly. Also, such construction eliminates pockets in Whith cuttings or sediment from the well bore might collect.

Thus, as fluid is circulated downwardly through the drill string 61 and discharged through the bit 69 on the lower end thereof, it is thereafter circulated upwardly through the well bore 60 in the annulus 63 surrounding the drill string 61. The arrangement of the recesses on the drill collar 68 enables the fluid to communicate substantially completely or circumferentially around the drill string throughout the extent of the portion of the drill string which has the recesses 66 provided thereon. Since the fluid may be communicated circumferentially of the recessed portion of the drill string 61 at all times, wall sticldng of the drill string is substantially reduced.

The form of recesses on the drill string 61 may be varied without departing from the scope of the present invention. For example, in FIG. 4, a drill string 61 is illustrated wherein a plurality of recesses is illustrated on the outer peripheral surface 67 of the drill string 61. It can be appreciated that the recesses 66 are again staggered so that their side portions overlap circumferentially and the recess ends are spaced longitudinally of the outer peripheral surface 67 as described with regard to FIGS. 1-3 of the drawings. The overlap of the side edges of the recesses circumferentially of the outer peripheral surface of the drill string 61 is represented at 78 in FIG. 4. In the form of the recesses shown in FIG. 4, the bottom surfaces 82 define cords on the transverse plane laterally of the longitudinal axis of the drill string 61.

In FIG. 5, the recesses 66 are arranged on the outer peripheral surface 67 of the drill string 61 as described with regard to the other forms of the invention shown in FIGS. 1-3 herein. However, the bottom surface 84 of each of the recesses 66 illustrated in FIG. 5 is concave in configuration on a plane transverse laterally of the longitudinal axis of the drill string 61.

In FIG. 6, a plurality of recesses 66 is again shown formed in the outer peripheral surface 67 of the drill string 61, wherein the recesses are arranged on 61 as described with regard to FIGS. 1-3. In the form of the invention shown in FIG. 6, the base or bottom surface of each of the recesses is illustrated as including a pair of intersecting planar surfaces 86 and 88. The planar surfaces 86 and 88 intersect on a line 87 within the recesses 66 as shown in sectional view in FIG. 6 which illustrates the planar surfaces 86 and 88 as being a pair of chordal lines intersecting at 87 and extending therefrom to the outer peripheral surface 67 of the member 61.

As a further example, FIG. 7 illustrates the drill string 61 as including a plurality of recesses 66 formed in the outer peripheral surface 67 of the drill string 61. It can be seen that the recesses 66 are staggered circumferentially but spaced longitudinally of the outer peripheral surface 67. The sectional view of FIG. 7 illustrates the adjacent side portions circumferentially overlapping at 91 as previously described with regard to FIGS. 1-3. In the form of the recesses shown in FIG. 7, the bottom surfaces 90 are convex in configuration on a plane transverse or laterally of the longitudinal axis of the drill string 61.

The recesses 66 shown in the embodiments of the invention illustrated in FIGS. 1 through 7, inclus've, have their ends 75b spaced longitudinally along the length of the drill string 61 so that there is no longitudinal overlapping of recesses, as previously described herein. The surface 67 extends uninterrupted between the recesses in a zig-Zag manner as shown in FIG. 2.

It can be appreciated from the foregoing description that the exact contour of the bottom surface in each of the recesses may vary without departing from the scope of the present invention. Also, the recesses may be ar ranged on the drill string 61 or any portion thereof in any manner as desired. As shown in the drawings, and more particularly, FIGS. 1 through 7 inclusive, the preferred form of the invention illustrates recesses 66 which extend longitudinally and laterally of the drill string 61; however, in some instances, it may be desirable to arrange the recesses at an angle relative to the longitudinal axis of the drill string 61.

An advantage of the present invention resides in the fact that the recesses 66 may be formed in the drill string 61 or in any portion thereof relatively quickly and without any substantial weight loss to the portion of the drill string which is recessed and without causing any undue stress concentrations in the portion of the drill string 61 which is recessed. Additionally, the recesses 66 by reason of their longitudinal and corcumferential extent provide a substantial fluid passage for communIcation of fluid in the annulus 63 circumferentially of the drill string 61 at all times. These features are extremely important in that they enable the present invention to accomplish its function without setting up or causing any deleterious effects or weak spots in any portion of the drill string. Also, the present invention reduces the chances of any cuttings or sediment in the mud laden drilling fluid in the annulus 63 from clogging or inhibiting fluid flow or communication circumferentially of the drill string which cuttings or sediment might cause or aid in causing the drill string to become stuck in the well bore 60.

Also, the present invention is particularly advantageous in that it enables not only a portion of the drill string, such as the drill collars, to be provided with a means for establishing and maintaining fluid communication circumferentially of the drill collars at all times within the well bore 60, but the present invention provides an economic and unique method of providing recessed areas throughout the longitudinal extent of the drill string. The recesses 66 may be provided in each tubular section of a drill string, or in those instances :where it may be desired to drill a well bore by means of a drill string which is formed of material other than metal and which is composed of either one long tubular member or several substantially long tubular members joined together (longer than those normally employed in drilling at the present time) the recessed areas can be provided or molded in such drill strings with a minimum of effort and at a substantial savings.

The present invention provides a means for interrupting the normal outer peripheral surface of a tubular drill string to accommodate fluid access circumferentially of the drill string, even when it is held against the side of the well bore. Also, the interruption of the normal outer surface of the drill string by a plurality of recesses occurs at a plurality of longitudinally and circumferentially spaced intervals on the drill string, as shown in the drawtags.

The configuration of the recesses shown herein tends to inhibit collection of cuttings and mud cake.

Broadly, the present invention relates to a drill string construction and means for establishing and maintaining fluid communication circumferentially of the drill string at all times during well drilling operations.

What is claimed is:

1. A tubular member adapted to be connected in a drill string for use in well drilling operations having an outer peripheral surface, a plurality of recesses in said surface, said recesses terminating in side portions, said recesses being circumferentially staggered in said outer surface whereby said side portions of successive, adjacent recesses overlap circumferentially, said recesses terminating end portions, said end portions of successive, adjacent recesses being spaced longitudinally of the tubular member, and

D said outer peripheral surface extending uninterruptedly between said recesses.

2. A tubular member for use in well bore drilling operations, comprising:

(a) an outer peripheral surface on the tubular member;

(b) a plurality of recesses spaced circumferentially in a row in said outer peripheral surface;

(c) there being a plurality of rows of recesses in said outer peripheral surface;

((1) said recesses having end portions and side portions;

(c) said side portions of said recesses in each row overlapping said side portions of said recesses in the next adjacent row; and

(f) said end portions of said recesses in each row being spaced longitudinally of said end portions of said recesses in the next adjacent row.

3. A tubular member for use in well bore drilling operations, comprising:

(a) an outer peripheral surface on the tubular member;

(b) a plurality of recesses interrupting said outer peripheral surface at circumferentially and longitudinally spaced intervals substantially throughout the longitudinal extent of the tubular member;

(c) said outer peripheral surface extending ruptedly between said recesses;

(d) said recesses terminating in end portions portions;

(e) said side portions of successive, adjacent recesses overlapping circumferentially; and

(f) said end portions of successive, adjacent recesses being spaced longitudinally of the tubular member.

4. A tubular member for use in well bore drilling operations, comprising:

(a) an outer peripheral surface on the tubular member;

(b) a plurality of recesses spaced circumferentially in a row in said outer peripheral surface;

(c) there being a plurality of rows of recesses in said outer peripheral surface;

(d) said outer peripheral surface extending betwcen said recesses in each row and between each row of recesses;

(e) said recesses terminating in end portions and side portions;

(f) said side portions of said recesses in each row overlapping said side portions of said recesses in the next adjacent row; and

(g) said end portions of said recesses in each row being spaced longitudinally of said end portions of said recesses in the next adjacent row.

5. A tubular member for use in well bore drilling operations, comprising:

(a) an outer peripheral surface on the tubular member;

(b) a plurality of recesses interrupting said outer peripheral surface at circumferentially and longitudinally spaced intervals substantially throughout the longitudinal extent of the tubular member;

uninterand side (c) successive, adjacent recesses overlapping circumferentially in said surface;

(d) successive, adjacent recesses being spaced longitudinally of the tubular member; and

(c) said outer peripheral surface extending uninterruptedly between said recesses.

6. The invention of claim 5 wherein said outer peripheral surface forms a circle on a section laterally of the longitudinal axis of the tubular member, said surfaces of said recesses forming in a section laterally of the longitudinal axis of the tubular member a chord in relation to the circle formed by said outer peripheral surface.

7. The invention of claim 5 wherein said outer peripheral surface forms a circle on a section laterally of the longitudinal axis of the tubular member, said recesses forming in a section laterally of the longitudinal axis of the tubular member concave surfaces on the tubular memher.

8. The invention of claim 5 wherein said outer peripheral surface forms a circle on a section laterally of the longitudinal axis of the tubular member, said recesses forming in a section laterally of the longitudinal axis of the tubular member convex surfaces on the tubular memher.

9. A tubular member for use in well drilling operations in a well bore filled with drilling fluid comprising:

(a) an outer peripheral surface;

(b) a plurality of recesses interrupting said surface at circumferentially and longitudinally spaced intervals;

(c) said recesses terminating in side portions;

(d) said recesses being staggered circumferentially in said outer surface whereby said side portions of successive adjacent recesses overlap circumferentially;

(e) said recesses terminating in end portions;

(f) said end portions of successive adjacent recesses being spaced longitudinally;

(g) said outer peripheral surface extending zig zag uninterruptedly between said recesses whereby turbulent flow is created in the drilling fluid around the tubuiar member.

References Cited by the Examiner UNITED STATES PATENTS 3/1964 Fox l75323 9/l964 Fox 641 References Cited by the Appiicant UNITED STATES PATENTS 2,999,552 9/1961 FOX.

FOREIGN PATENTS 564,188 2/1958 Belgium. 

1. A TUBULAR MEMBER ADAPTED TO BE CONNECTED IN A DRILL STRING FOR USE IN WELL DRILLING OPERATIONS HAVING AN OUTER PERIPHERAL SURFACE, A PLURALITY OF RECESSES IN SAID SURFACE, SAID RECESSES TERMINATING IN SIDE PORTIONS, SAID RECESSES BEING CIRCUMFERENTIALLY STAGGERED IN SAID OUTER SURFACE WHEREBY SAID SIDE PORTIONS OF SUCCESSIVE, ADJACENT RECESSES OVERLAP CIRCUMFERENTIALLY, SAID RECESSES TERMINATING END PORTIONS, SAID END PORTIONS OF SUCCESSIVE, ADJACENT RECESSES BEING SPACED LONGITUDINALLY OF THE TUBULAR MEMBER, AND SAID OUTER PERIPHERAL SURFACE EXTENDING UNINTERRUPTEDLY BETWEEN SAID RECESSES. 